Metal oxide semiconductor (MOS) nanomembranes hold a great potential for electronic devices. In this work, tubular SnO2 nanomembranes were fabricated by the rolled-up technology and investigated as the sensing element for chemiresistive gas sensors. Due to the high accessibility to both surfaces of nanomembranes and the large amount of adsorbed oxygen species, the sensor based on SnO2 nanomembranes displayed high and fast response for selective detection of acetone, as well as good repeatability, stability and low detection limit of ppb-level. The very good sensing performances derived from the tubular nanomembrane structure suggests a new platform that can be used for chemical gas sensors. This work will drive the integration of tubular MOS nanomembranes into a real microsensor based on the lab-in-tube concept.

Rolled-up SnO2 nanomembranes: A new platform for efficient gas sensors

P-type SnO thin films prepared by reactive sputtering at high deposition rates

Intrinsic and extrinsic doping contributions in SnO2 and SnO2:Sb thin films prepared by reactive sputtering

Refractive index (n), extinction coefficient (k), effective complex dielectric function (e) and band gap energy (Eg) of p-type SnOx thin films from 0.75 to 4 eV are studied. 25 nm thick films were deposited by direct current (DC) magnetron sputtering in reactive argon and oxygen atmosphere at different relative oxygen partial pressure (OPP) followed by a post annealing treatment at 250 °C in air atmosphere for 30 min. The relative high Hall effect mobility (μ) of the SnOx was attributed to the dominant SnO phase in films grown at 15% OPP. Films deposited at 5 and 11% OPP showed incomplete Sn oxidation resulting in a mixture of Sn and SnO phases with lower hole mobility. Optical transmittance (T) and reflectance (R) are described by assuming a model where the p-type SnOx films are defined by a dispersion formula based on a generalization of the Lorentz oscillator model. The roughness of the films (r) was modeled by a Bruggeman effective medium approximation (BEMA). From the optical analysis, k in the visible spectral region show high values for films with phase mixture, while films with single SnO phase presented negligible values. Films with single SnO phase have low n, this latter result from the lower compact microstructure of these films. Also, energies associated to direct and indirect transitions of the Brillouin zone of the SnOx films were identified from the evaluated e. Finally, the increase in the values of Eg energy was related to the increase in the SnO phase.

Sungdong Kim

Papers

Transparent SnO x thin films fabricated by radio frequency reactive sputtering with a SnO/Sn composite target

Comparative Analysis of SnOxThin Films Deposited by RF Reactive Sputtering with Different SnO/Sn Target Compositions